Putting in a gravel driveway

[Too many Kubotas]

The culvert needs to go in at the elevation the low area is. Then if that’s not deep enough build the road up high over it to get your depth of cover.

This is why I have so little above the recently lengthened culvert.

The elevation of the culvert is set by the ditch, and then the sections of driveway on the sides of it are where they are. I did not want a hump over the culvert, for a couple of reasons, snow plowing being one.

That's basically why I filled in the dip at the road end of the driveway. It was quite shallow, but a pain when plowing.

Will this hold up over time? Based on my experience, yes. The most weight it'll be subjected to with any regularity is 40,000 lbs., and with only about 16,000 on the heaviest axle. Other 12" culverts have lived through it, with less than half the dirt on top.

If for some reason it doesn't hold up I'll redo the ditch. I really prefer the whole thing to be as flat as possible. Looks a lot better that way, too.

 

[dodge man]

They make low clearance pipes that are stronger, usually concrete, and they make special shaped pipes, often called squash pipes.

 

[Too many Kubotas]

They make low clearance pipes that are stronger, usually concrete, and they make special shaped pipes, often called squash pipes.

If they're equally affordable and simple to lengthen, I may be interested at some point in the future.

 

[paulsharvey]

So, for humps, there are multiple good, or atleast workable solutions;
1- substandard coverage, could shorten life of the culvert, but can be fine for low traffic environment
2- a swale driveway, typically with a concrete or asphalt surface, allow water to flow, used for a shallow ditch, maybe a drive dips 6% away from the road, then up 6-10% at the back. Can have issues if you dont manage the swale right
3-ditch block drive; the drive has a small maybe 6" down from flush center, water stages up (and mostly soaks in), before flowing across; often not allowed, cause it causes water to sit, doesn't work so well in clay areas
4- Elliptical pipe; so, I think a 15" CMP equivalent is 12"x18"; 18" equivalent is 14x22; it's not a huge savings, but it can help; down side; ERCP is more money, and can be a bit more difficult to install;
5-instead of a single 24" say, maybe dual 18s, or possibly dual 15s; remember we are dealing with volume, so don't think that dual 15s= a single 30";
6- Fords; have a hard bottom surface, either rock, concrete, or engineered material like grates on the bottom, and rive through the water; pretty much not used in modern world, but it still works; got to have a water gauge visible, so you can clearly see your driving through 12" of water, not 36"

 

[paulsharvey]

If they're equally affordable and simple to lengthen, I may be interested at some point in the future.

Couple types; most common is ERCP; Elliptical reinforced concrete pipe. One catch; generally speaking, anyone's 18" RCP will home up fine with other manufacturers; ERCP, not so much. You can always do a "dissimilar pipe collar" which is butted up, wrapped in fabric, and a concrete band poured connecting both pipes, 360 degrees around, and over lapping both pipes.

Pipe Arc, has a flat bottom, and an arc on top, equal volume in a lower rise; never actually seen this installed; it kinda mimics old brick arc storm drains.

 

[paulsharvey]

As for equally affordable...

to the best of my knowledge, there is no poly or corrugated metal Elliptical pipe widely available, so, maybe we are talking 50% more per foot over RCP; but we are probably 2x or maybe 3x the cost of CMP or poly pipe for equivalent ERCP

 

[paulsharvey]

So, sample section of 1; $40/lf for 18" RCP vs $48/LF for 14x23 ERCP.

Also, note, this manufacters 18" equivalent is 14x23; some others are 14x22; that's what I meant about it being harder to mix/match

 

[Too many Kubotas]

Pipe Arc, has a flat bottom, and an arc on top, equal volume in a lower rise; never actually seen this installed; it kinda mimics old brick arc storm drains.

That would make me want to try cutting a 24" culvert in half.

Okay, it would surely sink in to some extent, so maybe starting with a 36". Or weld in some supports on the bottom to help keep the edges from sinking in.

 

[paulsharvey]

I found a manufacter of corrugated metal pipe arch in Penn. No idea on prices, and I have personally never seen this used down here

 

[paulsharvey]

That would make me want to try cutting a 24" culvert in half.

Okay, it would surely sink in to some extent, so maybe starting with a 36". Or weld in some supports on the bottom to help keep the edges from sinking in.

Those old brick arc systems used a flat mortared or poured brick floor, and then a self supporting arc "roof". I wouldn't do it without a "floor"